A superconducting magnet device is a device which generates strong magnetic force by applying electric power to a superconducting coil via electrodes. The superconducting coil needs to be cooled to liquid helium temperature in order to eliminate electric resistance of the superconducting coil. In order to generate strong magnetic force by cooling the superconducting coil down to liquid helium temperature, a conventional superconducting magnet device as shown in FIG. 23 includes, for example, a superconducting coil 1, electrodes 8 to supply current to the superconducting coil 1 when energized, and a cryostat 3 made of stainless steel to contain liquid helium 2 for cooling the superconducting coil 1 (for example, Patent Document 1).
When the liquid helium used for cooling evaporates, the volume significantly increases when compared with the liquid helium. Therefore, as shown in FIG. 23, for example, in a conventional superconducting magnet device, the cryostat 3 is provided with a helium gas release tube 3a to release evaporated helium gas to the outside (Patent Document 1).
Temperature outside of the cryostat 3 is higher than its inside temperature. When the heat outside is transferred to the inside of the cryostat 3, it may cause increase in volume due to the evaporation of the liquid helium, and increase in the inside temperature. In order to prevent the inside temperature from rising due to the outside heat, a conventional superconducting magnet device as shown in FIG. 23 includes, for example, a vacuum container 4 to house the cryostat 3, a heat shield 5 made of aluminum having high thermal conductivity to absorb the heat transferring to the vacuum container 4 from the outside, a heat transfer member 7 made of copper to transfer the heat absorbed by the heat shield 5 to gaseous helium 6 passing through the helium gas release tube 3a (for example, Patent Document 1). In the superconducting magnet device with such a configuration as shown in FIG. 24 and FIG. 25, for example, the heat transfer member 7 joined to the helium gas release tube 3a and disposed in a direction crossing the passing direction of the gaseous helium in the helium gas release tube 3a is protruding into the helium gas release tube 3a. The gaseous helium 6 passes through between the heat transfer member 7 and the helium gas release tube 3a from the downside to the upside. When the gaseous helium 6 passing through the helium gas release tube 3a comes into contact with the heat transfer member 7, the heat transferred from the outside and absorbed by the heat shield 5 is transferred to the gaseous helium 6 via the heat transfer member 7, and the gaseous helium 6 with the transferred heat is released to the outside by natural convection (for example, Patent Document 1).